Well seal assemblies which contain high pressure, highly corrosive well fluids by sealing the annulus between inner and outer concentric well members must not only resist the corrosive effects of the well fluids but must also resist movement of the seal ring from its desired position during the operation of running the assembly into the well and also after having been set and energized.
A prior art seal in such environment is shown in U.S. Pat. No. 4,043,391 wherein the seal ring is set by movement onto a larger diameter portion of the body on which it is mounted and the seal ring includes coil springs at its four corners to prevent their extrusion.
In an application filed Nov. 23, 1981, assigned Ser. No. 324,125, and now U.S. Pat. No. 4,381,114, a wellhead seal was disclosed including a resilient ring having a concave outer portion with upper and lower metal ring caps which are held in sealing engagement with their respective sealing surfaces responsive to fluid pressure which is exerted on the outer concave surface of the resilient ring.
While both of the above seals have been used to provide a desired annulus seal, the second seal assembly cannot be energized within a well bore and the first seal assembly does not protect against corrosive fluids.
Another prior well annulus seal is disclosed in U.S. Pat. No. 3,797,864. This seal includes a resilient packing ring positioned between upper and lower support rings and energized by axial loading to cause the packing ring and lips on the support rings to move radially outward and inward into engagement with opposite surfaces of the annulus.